Generally, in a construction machine such as a hydraulic shovel, an engine (particularly diesel engine) is widely employed as a power source. However, exhaust gas discharged from an engine contains a large amount of nitrogen oxide (NOx). Thus, conventionally, various exhaust gas purifying devices for removing nitrogen oxide within and purifying exhaust gas have been put into practical use. As an example of such exhaust gas purifying device, one in which a reducing agent such as urea water is injected into an exhaust gas path of an engine to reduce nitrogen oxide has been known. In the case of employing the exhaust gas purifying device using the reducing agent, a reducing agent tank for storing the reducing agent such as urea water is mounted on a machine body.
Upon mounting the reducing agent tank to the machine body, the reducing agent needs to be supplied appropriately to the reducing agent tank. Therefore, accessibility upon supply is required, and as great an increase as possible in the capacity of the reducing agent tank is required in order to decrease the number of supplies. However, many instruments and devices are mounted on a construction machine such as a hydraulic shovel, and it is difficult to ensure additional space for the reducing agent tank.
Thus, conventionally, a configuration in which a control valve controlling the operation of a hydraulic actuator and the reducing agent tank are both arranged in an instrument accommodating chamber provided on the front section of an upper slewing body of a hydraulic shovel (see PTL 1) has been known. Also, a configuration in which a control valve and a reducing agent tank are arranged together in an instrument chamber provided on the front section of an upper slewing body of a hydraulic shovel and in which intake and exhaust openings and a fan for intake and exhaust are provided in the same instrument chamber (e.g., see PTL 2) has been proposed.